Existing cold food counter designs such as that illustrated in FIG. 1 typically include an open interior liner 10 formed of stainless steel into which a pan or similar food-containing utensil is placed. Insulation 14 surrounds the enclosed sections of liner 10, which insulation 14 in turn is enclosed within an exterior metal liner 18. Tangentially contacting the surface 22 of the interior liner 10 opposite the food-containing pan is copper tubing 26 through which cooling fluid circulates. Because tubing 26 contacts this exterior surface 22 of the interior liner 10 only tangentially, the resulting cooling effect on the volume within interior liner 10 is diminished, limiting the counter's ability to maintain food products in the pan at a suitable temperature. This limited cooling surface similarly precludes use of fans or other air moving systems to enhance the effectiveness of the counter, as doing so would merely defrost liner surfaces and ultimately increase, rather than decrease, resulting temperatures. Consequently, existing commercial counters continue to be static ones lacking substantial airflow.
U.S. Pat. No. 2,463,104 to Hender illustrates an open-top display case in which refrigerant-carrying pipes are similarly arranged about the exterior surface of the interior liner or container. Unlike current static commercial cold food counters, however, the display case disclosed in the Hender patent includes fans positioned outside the container. The fans function to draw air into the container and then circulate it along the container's exterior surfaces, past the pipes and over the container sides. Although this cooled air can then be redrawn into the container, ambient air is drawn with it, subjecting food within the container to other than solely cooled air. Drawing ambient air through the container also increases the possibility of food contamination through contact with bacteria and other particulate matter present in the ambient air.
U.S. Pat. No. 4,840,040 to Fung discloses a similar display cabinet in which cooling coils are placed adjacent the exterior surface of a panel. As with the display case of the Hender patent, that illustrated in the Fung patent utilizes a fan to draw air into the display space and circulate it past the external coils. The process too draws ambient air into the display space, decreasing the cooling capability of the air passing through that space. By ducting air between the display space wall exteriors and the interior walls of the display counters or cases, the systems described in both the Hender and Fung patents should also cause the air flowing through the food-containing spaces to be essentially non-turbulent (i.e. laminar).
Current industry and governmental health and safety regulations, moreover, require food-containing utensils to be elevated above their respective counter surfaces. Existing commercial utensils thus include lips or flanges around their upper perimeters that are supported by the counter surfaces. This relationship between flange and counter surface prevents food from spilling into the interiors of the counters. At the same time, however, it effectively seals that interior from the ambient environment, precluding air circulation as proposed in the Hender and Fung patents.